Endoscopes are used to perform a variety of surgical procedures. FIGS. 1 and 2 illustrate an embodiment of a conventional endoscope. It has a handle from which extends a flexible shaft, which is inserted into a hollow organ to be inspected. The shaft consists of a proximal section, insertion tube, bending section and a stiff section. The shaft terminates in the distal end, which typically houses image lens, illumination bulb, air/water nozzle and an instrument channel outlet. Light is transmitted from a light source through the shaft via an electric cable to the illumination bulb. The illumination bulb illuminates the area to be examined. The image lens captures images of the illuminated area. The image is then transmitted through a fiber optic cable and viewed through an eyepiece on the handle of the endoscope. Alternatively, the image is converted to a video signal and transmitted to an image processor by an electrical cable. The image is then processed and displayed on a display unit like a computer monitor. The handle of the endoscope has an extension arm that attaches the endoscope to a light source and an image processor.
To enable the endoscope to maneuver through the turns of a hollow organ the shaft is flexible and incorporates a multitude of cables that attach the bending portion with actuators. Tension is applied to these cables to move the bending portion in various directions. This is done by manual adjustment of actuators on the handle of the endoscope. Typically, there are two pairs of such cables passing within the shaft, one pair for flexing the bending portion in one plane and the other pair for flexing it in an orthogonal plane.
It is also usual to provide two channels extending between the handle and the distal end of the shaft, an air/water channel and an instrument channel. The air/water channel is used to insufflate air in a hollow organ to expand it for proper visualization. The air/water channel is connected proximally to an air/water pump (not shown) and to distally to the air/water channel outlet. The image lens and the illumination bulb are frequently smeared with blood, stool or other body fluids while in a hollow organ which obstructs a clear view. In such a situation, the air/water channel is used to eject water or blow air at the image lens and/or illumination bulb in order to clean them while still inside a hollow organ. The instrument channel has an inlet proximally and an outlet distally. It is used to pass various surgical instruments to do various surgical procedures. It is also used to apply suction to remove fluids, air and other materials from within a hollow organ during examination.
Endoscope is typically inserted into the patient either thorough a natural body orifice like anus or mouth or it is inserted through a surgical incision. It is then steered to a desired location by adjusting the bending portion and manually pushing the endoscope. After reaching the desired location, the endoscope is withdrawn. Typically it is during pullout when the inside of a hollow organ like colon is thoroughly examined. Insertion of the endoscope into a hollow organ is a risky maneuver and is associated with significant complications like trauma, bleeding and perforation. It is generally desirable to complete the examination with a single insertion to minimize complications.
The present endoscopes have significant limitations. As shown in FIG. 3 they are only forward viewing. Currently, rear view can only be obtained by bending the distal portion of the endoscope back upon itself in a ‘retro flexion’ maneuver as shown in FIG. 4B. However, it is not possible to achieve retro flexion in many narrow hollow organs like colon, esophagus, duodenum and small bowel. Also, retro flexion compromises forward view. Hence with conventional endoscopes, only one view, forward or backward, is possible at a given time. The present endoscopes also have a narrow field of vision with an angle of vision of about 120 degrees. A large number of significant pathologic findings are frequently missed during endoscopic examination because the inability to obtain rear view and a narrow field of vision of conventional endoscopes.
This is especially true for colonoscopy where the inside of the colon is examined with an endoscope. Many cancers and pre cancerous lesions (polyps) are frequently missed during colonoscopy (Pickhardt et al, New England Journal of Medicine 2003; 349: 2191-2200). This has serious consequences including death, many of which can easily be prevented. Majority of the missed lesions lie on the rear side of mucosal folds (Pickhardt et al; Annals of Internal Medicine 2004; 141: 352-360). With forward viewing endoscopes, the front of mucosal folds obstructs visualization of the rear side as shown in FIG. 4A. Currently, the rear side of a mucosal fold can only be examined by pushing the tip of the endoscope beyond the fold and bending the endoscope back upon itself in a ‘retro flexion’ maneuver as shown in FIG. 4B. However, it is frequently not possible to achieve retro flexion in a narrow hollow organ like colon.
Also, retro flexion maneuver compromises the forward view. With conventional endoscopes, only one view, forward or backward, is possible at a given time. Complete examination of colon that includes both forward and rear views currently requires multiple insertions, one to obtain forward view and other to obtain backward view by retro flexion. Both, retro flexion and multiple insertions, independently increase the morbidity, mortality, time and cost of colonoscopy. Moreover, intra colonic retro flexion can not be obtained frequently because of a narrow colonic lumen. Also, conventional endoscopes have a narrow field of vision of about 120 degrees. Some lesions that are missed lie outside of the field of view of conventional endoscopes.
The rear side of the mucosal folds is also hard to access with conventional endoscopes, which have the instrument channel outlet only on the distal end. These areas can only be visualized by retro flexion, which narrows and sometimes obliterates the lumen of the instrument channel. Also, many surgical instruments are not flexible enough to follow the path of a retroflexed endoscope. It is difficult and many times impossible to pass surgical instruments through the instrument channel when the endoscope is retroflexed and surgical procedures can not be performed on the rear side of the mucosal folds.